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The law of treaty reservations - which enables states to ask that their multilateral obligations be tailored to their individual preferences - has been controversial for over fifty years, and is at present subject to pitched battles within (and between) the International Law Commission and numerous other international institutions. There is broad agreement that existing scheme under the Vienna Convention on the Law of Treaties involves a sharp tradeoff between honoring the unalloyed consent of non-reserving states (that is, those agreeing to the treaty as originally negotiated, which may object to proposed reservations) and respecting the conditioned consent of reserving states; moreover, it is thought to decisively favor the latter, leading to a surplus of treaty reservations and a paucity of objections to them. The ambiguities that pervade the Convention are said to play a supporting role. Whatever their cause, it is thought, such ambiguities tend to disadvantage non-reserving states; the straightforward solution is to resolve those ambiguities, preferably by making reservations harder to pull off.

This approach is seriously flawed. In fact, the law of treaty reservations - understood as reflecting, rather than surmounting, its frustrating ambiguities - plausibly serves the interests of its supposed victims, the non-reserving states, perhaps even to a greater degree than for inveterate reservers. Treaty reservations not only increase the breadth of treaty participation, but permit agreement on broader commitments than would otherwise be possible. These effects inure to the benefit of reserving and non-reserving states alike. But deeper commitments, coupled with reservations, also establish a reliable, low-cost mechanism for providing information on reserving states, something facilitated by the existing scheme's eccentricities. Those same eccentricities also enable non-reserving states to reserve their own judgment regarding the acceptability of reservations, and thus shift risk control back (somewhat) in their favor.

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No. 329

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